Sone machine shops typically operate machines, such as milling machines, lathes, and the like, at reduced rates, typically one-third to one-half the full capacity, in order to avoid breaking the tool when manufacturing an inexpensive part, e.g., the bit may cost fifteen dollars but the part may cost only five dollars.
Other machine shops may manufacture parts which are more expensive, typically costing hundreds or thousands of dollars to manufacture. The parts produced by large machine shops are usually complex and must conform to strict specification requirements provided by the customer. To insure the machined part meets these strict specification requirements, the machine operator typically reduces the rate (e.g., advance speed) of the machine tool in order to increase the accuracy of the cutting bit and to improve the quality of the machined surface of the workpiece. Using conventional machining processes, the operator relies on visual, auditory, and vibration cues to adjust the spindle speed, depth of cut, and rate of advance of the cutting tool to insure a proper surface finish of the workpiece. Post inspection of the workpiece surface finish is required and any deviation from the specification requirements is discovered only after the workpiece is complete and may result in the expensive machined part being scrapped.
Thus, in both types of machine shops, it would be advantageous if the machine operators were provided with real time information concerning the current state of the machine tool (e.g., the remaining tool life, and whether the tool is worn or damaged) because the state of the machine tool directly affects the quality of the surface finish of the workpiece being manufactured and the operating capacity of the machine. Currently, the state of the machine tool is typically determined subjectively by relying on a trained operator's ear, vibration cues and/or shutting the machine down to visually inspect the machine tool.
Other key factors which affect the surface finish of the workpiece include proper coolant/lubricant flow and how well the workpiece is secured in the machine clamp. Similar to the above, machine operators currently rely on visual, auditory and vibration cues to determine proper lubricant flow and the security of the workpiece in the clamp of the machine.
The result is that both types of machine shops lose productivity because they lack real-time feedback instrumentation that characterizes the machining process.